Power efficient PS-Poll

ABSTRACT

A IEEE 802.11 Wireless Local Area Network (WLAN) system of an access point (AP) and one or more stations (STAs) reduces power consumption and increases battery life of power efficient low power STAs by decreasing the amount of time that a power efficient low power STA remains in an awake state. After indicating power efficient low power operation during association with an AP supporting such operation, the power efficient low power STA may enter the doze state from the time that the power efficient low power STA sends a PS-Poll until the power efficient low power STA receives the buffered DATA frame from the AP. While implementing the power efficient PS-Poll method, the AP can send the buffered DATA frame to the STA SIFS after the AP sends an ACK to the received PS-Poll from the STA.

The present application is a continuation of U.S. patent applicationSer. No. 15/365,600, entitled “POWER EFFICIENT PS-POLL,” filed on Nov.30, 2016, which is a continuation of U.S. patent application Ser. No.15/213,107, entitled “POWER EFFICIENT PS-POLL,” filed on Jul. 18, 2016,which is a divisional of U.S. patent application Ser. No. 13/685,341,entitled “POWER EFFICIENT PS-POLL,” filed on Nov. 26, 2012, all of whichare incorporated herewith in their entirety. The present applicationalso incorporates by reference the subject matter of: U.S. ProvisionalPatent Application Ser. No. 61/676,196 entitled “POWER EFFICIENTPS-POLL,” filed on Jul. 26, 2012; U.S. Provisional Patent ApplicationSer. No. 61/676,201 entitled “SLOT-BASED POWER SAVE IMPROVEMENT,” filedon Jul. 26, 2012; and U.S. Provisional Patent Application Ser. No.61/676,173 entitled “SLOT-BASED POWER SAVE WITHOUT PS-POLL,” filed onJul. 26, 2012.

BACKGROUND

Devices using Institute for Electrical and Electronic Engineers (IEEE)802.11 and/or Wireless Local Area Network (WLAN) connectivity forInternet access are frequently either battery-powered or otherwisebenefit from minimizing power consumption, particularly when not beingutilized. For example, IEEE 802.11ah is considered suitable for use forsensor applications, such as a smart grid application, in which thestations are battery powered and should work for a long time withoutreplacement of the battery. The Distributed Coordination Function (DCF)of IEEE 802.11 provides a power saving mechanism (PSM) allowing nodes toremain silent in a sleep state. However, various issues can cause actualuse of the PSM to unnecessarily consume power.

There is, therefore, a need in the art for alternative power savemechanisms in using wireless network connections.

SUMMARY

Various disclosed embodiments relate to Wireless Local Area Network(WLAN) systems and methods for implementing a power efficient PS-Pollmethod. According to the present disclosure, a power efficient low powerstation is associated with an access point to form a basic service set.The power efficient low power station and the access point (AP) areconfigured to implement a power efficient PS-Poll method. Whileimplementing the power efficient PS-Poll method, the AP indicates in theresponding acknowledge (ACK) frame to a PS-Poll from a power efficientlow power station whether the AP will delay the buffered DATAtransmission after the responding ACK. While implementing the powerefficient PS-Poll method, the AP can send the buffered DATA frame to thepower efficient low power station SIFS after the AP sends ACK to thereceived PS-Poll from a low power station. While implementing the powerefficient PS-Poll method, the power efficient low power station isallowed to enter a doze state in the time between the time that thepower efficient low power station transmits the PS-Poll and the timethat the power efficient low power station received the buffered DATAframe from the AP. When the AP and the station implement the powerefficient PS-Poll method, the AP and the STA may also need to implementa transmission opportunity (TXOP) power save method.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, wherein likenumbers designate like objects, and in which:

FIG. 1 depicts a wireless local area network (WLAN) environment in whichpower efficient power save poll (PS-Poll) stations in accordance withvarious embodiments of the present disclosure are implemented;

FIGS. 2A and 2B depict timelines for a portion of communications withina WLAN environment including PS-Poll stations operating a PS-Pollprocedure;

FIG. 3 depicts a timeline illustrating operation of a low power, powerefficient PS-Poll, station in accordance with the present disclosure;

FIGS. 4A and 4B depict timelines illustrating operation of a low power,power efficient PS-Poll, station in accordance with the presentdisclosure; and

FIGS. 5 and 6 depict high level flow charts for processes performedwithin a WLAN environment including enhanced low power, power efficientPS-Poll, stations in accordance with various embodiments of the presentdisclosure.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words or phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, whether such a device is implemented in hardware, firmware,software or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermight be centralized or distributed, whether locally or remotely.Definitions for certain words and phrases are provided throughout thispatent document, and those of ordinary skill in the art will understandthat such definitions apply in many, if not most, instances to prior aswell as future uses of such defined words and phrases. While some termsmay include a wide variety of embodiments, the appended claims mayexpressly limit these terms to specific embodiments.

DETAILED DESCRIPTION

FIGS. 1 through 6, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system.

FIG. 1 illustrates a wireless local area network (WLAN) environment inwhich power efficient PS-Poll in accordance with various embodiments ofthe present disclosure are implemented. WLAN environment 100 includes abasic service set (BSS) 115 of an IEEE 802.11 wireless local areanetwork. WLAN environment may be implemented, for example, in accordancewith IEEE P802.11ac/D2.0, Draft STANDARD for InformationTechnology—Telecommunications and information exchange betweensystems—Local and metropolitan area networks—Specific requirements Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)specifications Amendment 4: Enhancements for Very High Throughput forOperations in Bands below 6 GHz, the content of which is incorporatedherein by reference. The BSS 115 includes, in the simplistic exampleshown, an access point (AP) 110 that is connected to the Internet (notshown) and a plurality of stations (STAs, also called “nodes” or“clients”) 120 a and 120 b located within coverage area 130 of AP 110.STAs 120 a and 120 b are visible to the AP 110 and can communicate withthe AP 110. The reception area 140 a is the coverage area of STA 120 a,and reception area 140 b is the coverage area of STA 120 b.

Although certain details will be provided with reference to thecomponents of the access point 110 and the STAs 120 and 120 b (singly,“WiFi device”), it should be understood that other embodiments mayinclude more, less, or different components. A WiFi device includeselectrical processing circuitry, a transmitter, and a receiver. Incertain embodiments, the WiFi device includes a transceiver. Theprocessing circuitry performs the functions of the WiFi device, with aidfrom the other components within the WiFi device. The processingcircuitry includes a processor coupled to a memory and other componentswithin the WiFi device. The memory includes any suitable volatile ornon-volatile storage and retrieval device(s). For example, the memorycan include any electronic, magnetic, electromagnetic, optical,electro-optical, electro-mechanical, or other physical device that cancontain, store, communicate, propagate, or transmit information. Thememory can store data and instructions for use by the processor.

PS-Poll Procedure

FIGS. 2A and 2B depict alternative timelines for a portion ofcommunications employed during PS-Poll procedures. As illustrated bytimelines 200 and 202, a STA 120 a or 120 b may “doze” or “sleep” in lowpower operation during an interval 250 or 260 prior to or aftertransmission of a BEACON 210 by the AP 110. When a STA 120 is in a Dozeor Sleep state, the STA 120 cannot send or receive communication signalsbetween the STA 120 and the access point 110. When a STA 120 is in anAwake state, the STA 120 is able to sense the communication channelbetween the STA 120 and the access point 110 and to send and receivecommunications. The STA 120 a or 120 b may wake up for the BEACON 210,then transmit PS-Poll frame 212, and then must stay awake during thesubsequent interval 251 during which STA 120 a or 120 b transmits aPS-Poll frame 212, receives and acknowledgement (ACK) frame 214, andreceives data 216. The STA 120 a or 120 b may transmit PS-Poll frame 212without receiving the BEACON, and then must stay awake during thesubsequent interval 261 during which STA 120 a or 120 b transmits aPS-Poll frame 212, receives and acknowledgement (ACK) frame 214, andreceives data 216. As shown, the ACK 214 contains a traffic buffering(BU) bit set to a logical one (1), indicating that traffic for the STAis buffered as indicated in the traffic indication map (TIM) such thatthe STA must stay awake (i.e. a service period starts). The BU set to alogical zero (0) indicated that no traffic is buffered for the STA andthe STA may go back to sleep. When traffic (for example, a buffered DATAframe) is present at the AP 110 for that STA, the traffic is said to beapplicable to that STA, such as applicable buffered DATA.

Upon receiving the data 216 from the AP 110, the STA 120 a or 120 btransmits ACK to the AP 110 and then goes back to sleep for interval252, which interval includes the occurrence of another BEACON 218transmission. Once a power save STA 120 a or 120 b sends a PS-Poll frame212, however, that STA 120 a or 120 b needs to keep awake until the nextbeacon or data frame from the AP 110. This increases the powerconsumption of a power save STA.

TXOP Power Save in 802.11ac

An AP 110 may indicate to the STAs 120 a and 120 b support fortransmission opportunity (TXOP) power save operation (a power managementscheme in which a STA may either be in the Awake or Doze state during aTXOP obtained by the AP for transmissions), and whether the AP 110allows use of TXOP power save in a specific TXOP. In certain embodimentsof the present disclosure, the indication of support for TXOP power saveoperation is included within a BEACON 301 frame. A TXOP power save STA120 a or 120 b may go to Doze state if (a) the AP 110 allows the STA touse TXOP power save in a specific TXOP, and (b) a Physical LayerConvergence Protocol (PLCP) Protocol Data Unit (PPDU) scheduled for thatspecific TXOP is not intended for delivery to the STA.

Power Efficient Power Save PS-Poll

In a normal PS-Poll procedure, once a power save STA sends PS-Poll to anAP, the STA will need to keep active until a buffered DATA frame isreceived from the AP. If the AP cannot send the buffered DATA frame tothe power save STA after receiving a PS-Poll, the AP just sends aresponding ACK then sends the buffered DATA frame later. A power saveSTA will waste more power because of such operations. While implementingthe power efficient PS-Poll method, the AP indicates in the respondingACK to a PS-Poll from a power efficient low power STA whether the APwill delay the buffered DATA transmission after the responding ACK.While implementing the power efficient PS-Poll method, the AP can sendthe buffered DATA frame to the power efficient low power STA SIFS afterthe AP sends ACK to the received PS-Poll from a power efficient lowpower STA. While implementing the power efficient PS-Poll method, thepower efficient low power STA is allowed to go to doze state in the timeperiod from the time that the power efficient low power station sendsPS-Poll to the time that the power efficient low power STA receives thebuffered DATA frame from the AP. When the AP and the STA implement thepower efficient PS-Poll method, the AP and STA may also need toimplement a TXOP power save method.

Power Efficient Power Save PS-Poll 1

FIG. 3 is a timeline illustrating operation of a power efficient PS-Polllow power STA in accordance with one embodiment of the presentdisclosure. An AP 110 indicates (via an information element within theBEACON 401, 461 or within the ACK 405, 463) whether the AP 110 supportspower efficient low power STAs, and if so that AP 110 shall allow TXOPpower save in all TXOPs during a period after at least a PS-Poll isreceived and before sending a buffered data frame to all power efficientlow power STAs from which the AP 110 receives a PS-Poll. After a powerefficient low power STA sends a PS-Poll, if the first PPDU does notinclude a Message Protocol Data Unit (MPDU) for that power efficient lowpower STA in a TXOP, the STA (having previously announced being a powerefficient low power STA) can enter the Doze state in the TXOP.

Timeline 300 relates to AP 110, a non-low power STA, and a powerefficient low-power STA, with the transmissions from the three nodesdepicted separately for clarity and intervals during which the powerefficient low power STA 120 enters different states identified. Duringthe interval 350 prior to the AP 110 transmitting a BEACON 301, thepower efficient low power STA 120 may be in the Doze state. The powerefficient low power STA 120 wakes up during the interval 351 in whichthe BEACON 301 is transmitted, and until the start of transmission of anaggregated MPDU (A-MPDU) 302 by the non-low power STA to the AP 110. Thepower efficient low power STA 120 immediately enters a Doze state at thestart of the A-MPDU 302 after determining that the A-MPDU is for anotherstation through, e.g., information in the physical (PHY) signal. Duringthe interval 352 following the start of transmission of the A-MPDU 302,including transmission of a Block ACK (BLK ACK) 303 from the AP 110 tothe non-low power STA, the power efficient low power STA 120 returns tothe Doze state. In certain embodiments, the BEACON frame includes a TIMIE that indicates the presence of buffered DATA frames and indicates theSTAs to which the DATA frames are applicable. When a power efficient lowpower STA receives a TIM IE that indicates that none of the bufferedtraffic is applicable to that power efficient low power STA, the powerefficient low power STA is in a Doze state throughout the remainder ofthe that Beacon interval.

The power efficient low power STA 120 wakes up again during the interval353 in which the power efficient low power STA 120 transmits a PS-Poll304 to the AP 110, and receives in return an ACK 305 with the BU setto 1. The power efficient low power STA 120 then re-enters the Dozestate during a subsequent interval 354, during which the non-low powerSTA transmits another A-MPDU 306 to the AP 110 and receives a BLK ACK307 from the AP 110. The power efficient low power STA 120 awakes againfor the interval 355 during which the AP 110 transmits buffered data 308to the power efficient low power STA 120 and during which the low powerSTA 120 transmits an ACK 309 to the AP 110, before returning once moreto the DOZE state for the interval 356 following transmission of the ACK309.

Power Efficient Power Save PS-Poll 2

FIGS. 4A and 4B are timelines illustrating operation of a powerefficient low power STA 120 power save PS-Poll in accordance withanother embodiment of the present disclosure. Once again a powerefficient low power STA 120 is defined, and an AP 110 can indicatewhether the AP 110 supports power efficient low power STA 120. If so andthe AP 110 receives a PS-Poll from a power efficient low power STA 120that AP shall send a data frame to the power efficient low power STA 120following either a SIFS or a Point Coordination Function (PCF)Inter-Frame Space (PIFS) after the AP transmits the ASK to acknowledgethe PS-Poll from the power efficient low power STA 120.

Timeline 400 relates to AP 110, a non-low power STA, and a powerefficient low-power STA 120, with the transmissions from the three nodesdepicted separately for clarity and intervals during which the powerefficient low power STA 120 enters different states identified. Duringthe interval 450 prior to the AP 110 transmitting a BEACON 401, thepower efficient low power STA 120 may be in the Doze state. The powerefficient low power STA 120 wakes up during the interval 451 in whichthe BEACON 401 is transmitted, and until the start of transmission ofA-MPDU 402 by the non-low power STA to the AP 110. During the interval452 following the start of transmission of the A-MPDU 402, includingtransmission of BLK ACK 403 from the AP 110 to the non-low power STA,the power efficient low power STA 120 returns to the Doze state.

The power efficient low power STA 120 wakes up again during the interval453 in which the power efficient low power STA 120 transmits a PS-Poll404 to the AP 110, and receives in return an ACK 405 with the BU setto 1. The power efficient low power STA 120 remains awake duringtransmission, after a SIFS, by the AP 110 of buffered data 408 to thepower efficient low power STA 120 and to transmit an ACK 409 to the AP110. The power efficient low power STA 120 then returns once more to theDOZE state for the interval 454 following transmission of the ACK 409.

Timeline 460 relates to a similar series of transmissions involving AP110 and a power efficient low power STA 120 only, without transmissionsby a non-low power STA. During the interval 490 prior to the AP 110transmitting a BEACON 461, the power efficient low power STA 120 may bein the Doze state and may remain in that state during transmission ofBEACON 461 until shortly before the power efficient low power STA 120transmits a PS-Poll 462 to the AP 110. The power efficient low power STA120 then remains awake through the interval 491 during which an ACK 463is received from the AP 110, buffered data 464 is transmitted by the AP110 (after a SIFS), and an ACK 465 is transmitted to the AP 110 by thepower efficient low power STA 120. The power efficient low power STA 120then returns once more to the DOZE state for the interval 492 followingtransmission of the ACK 465.

FIG. 5 depicts a process or method 500 executed within a STA 120 forimplementing a low power, power efficient PS-Poll. FIG. 6 depicts aprocess or method 600 executed within an AP for implementing a lowpower, power efficient PS-Poll. The embodiments of the processes 500 and600 shown in FIGS. 5 and 6, respectively, are for illustration only.Other embodiments could be used without departing from the scope of thisdisclosure.

When the power efficient low power STA associates with the AP to jointhe BSS, the STA knows that the AP supports low power STA operationthrough the Association Response, and the AP knows that the STA is apower efficient low power STA through the Association Request.

An AP transmits a BEACON frame, which includes a traffic indication map(TIM) information element (IE) in Block 610. Within the BEACONtransmission, the AP sends an indication to the power efficient lowpower STAs 120 that the AP 110 supports power efficient low power STAs(i.e. STAs that implement a power efficient PS-Poll procedure, such as aTXOP power saving procedure). The power efficient low power station 120is awake during the BEACON transmission to receive the BEACON when thepower efficient low power station wants to receive the TIM. Otherwisethe power efficient low power station just remains in the doze stateduring the AP's beacon transmission until the power efficient low powerSTA decides to send Ps-Poll to ask the AP whether there is bufferedtraffic in the AP for the STA. The power efficient low power STAreceives the TIM IE that is within the BEACON in Block 510. The powerefficient low power STA receives the indication that the AP supportsTXOP power saving stations in Block 520. In Block 530, in response toreceiving the TIM IE in Block 510, the power efficient low power stationenters a Doze state.

In certain embodiments, the power efficient low power STA remains awakeafter receiving the TIM IE to immediately send a PS-Poll to the AP. Thepower efficient low power STA is awake to send a PS-Poll frame to the APin Block 540. The STA indicates to the AP that the STA is a powerefficient low power station with power efficient PS-Poll capabilitiesthrough the association procedure when the STA joins the BSS (e.g., inan Extend Capabilities Information Element within a Probe Request andAssociation Request). The AP receives the PS-Poll from the powerefficient low power STA in block 620. The PS-Poll triggers the AP tosend any buffered DATA frames allocated to the power efficient low powerstation that sent the PS-Poll.

In response to receiving the PS-Poll, the AP determines certainrequirements (i.e., actions the AP shall do) in Block 630. When the APsupports power efficient low power STA operation, which implies TXOPpower saving operation, in response to receiving a PS-Poll, the AP shallallow TXOP power save in all TXOPs before the AP sends the buffered DATAframe to the power efficient low power STA from which the AP received aPS-Poll. In response to receiving a PS-Poll, the AP shall do one of thefollowing: (1) send a DATA frame to the power efficient low power STASIFS after receipt of the PS-Poll when the data is ready (sometimes theAP cannot immediately transmit a buffered frame for the STA that sendsthe PS-Poll); (2) send an ACK to the power efficient low power STA fromwhich the PS-Poll was sent and after a SIFS, send a DATA frame to thelow power STA; (3) send an ACK to the power efficient low power STA fromwhich the PS-Poll was sent and, after a SIFS, send a DATA frame to thelow power STA; or (4) send an ACK to the power efficient low power STAfrom which the PS-Poll was sent and, after a PIFS, send a DATA frame tothe power efficient low power STA (this DATA frame after ACK gives theAP more time to prepare to transmit the buffered frame to the powerefficient low power STA). The AP needs to include an indication in theACK to the STA when the AP will do (2) or (3).

The power efficient low power STA remains awake after sending thePS-Poll to receive an ACK from the AP. The power efficient low power STAresponds to the ACK in Block 550, by remaining in an Awake state orentering a Doze state. When the AP informs the power efficient low powerSTA that the AP cannot immediately transmit the buffered traffic to thepower efficient low power STA through an indication in the ACK, then thepower efficient low power STA enters a Doze state 354 in Block 550—e.g.,once the STA detects a TXOP that is for another STA. When the AP informsthe power efficient low power STA that the AP will immediately transmitthe buffered traffic to the STA through the indication in the ACK, thenthe power efficient low power STA remains awake, awaiting a bufferedDATA frame transmission from the AP.

The AP sends buffered DATA to the power efficient low power station inblock 640. If the power efficient low power STA is in a Doze stateshortly before the AP sends the buffered data, then the power efficientlow power STA awakens early enough to receive the DATA frametransmission. The power efficient low power STA, in an Awake state,receives the buffered DATA from the AP in Block 560. In response toreceiving the DATA frame, the power efficient low power STA sends an ACKto the AP and then enters a Doze state in Block 570.

It is important to note that while the present disclosure includes adescription in the context of a fully functional system, those skilledin the art will appreciate that at least portions of the mechanism ofthe present disclosure are capable of being distributed in the form ofinstructions contained within a machine-usable, computer-usable, orcomputer-readable medium in any of a variety of forms, and that thepresent disclosure applies equally regardless of the particular type ofinstruction or signal bearing medium or storage medium utilized toactually carry out the processes 500 and 600. Examples of machineusable, machine readable or computer usable, computer readable mediumsinclude: nonvolatile, hard-coded type mediums such as read only memories(ROMs) or erasable, electrically programmable read only memories(EEPROMs), and user-recordable type mediums such as floppy disks, harddisk drives and compact disk read only memories (CD-ROMs) or digitalversatile disks (DVDs).

It may be advantageous to set forth definitions of certain words andphrases used throughout this patent document: the terms “include” and“comprise,” as well as derivatives thereof, mean inclusion withoutlimitation; the term “or,” is inclusive, meaning and/or; the phrases“associated with” and “associated therewith,” as well as derivativesthereof, may mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like. The term“device” means any apparatus, system, machine, thing, item, construct,or any part thereof. The term “controller” means any device or partthereof that controls at least one operation, such a device may beimplemented in hardware, firmware or software, or some combination of atleast two of the same. It should be noted that the functionalityassociated with any particular controller may be centralized ordistributed, whether locally or remotely. Definitions for certain wordsand phrases are provided throughout this patent document, those ofordinary skill in the art should understand that in many, if not mostinstances, such definitions apply to prior uses, as well as future uses,of such defined words and phrases.

While this disclosure has described certain embodiments and generallyassociated methods, alterations and permutations of these embodimentsand methods will be apparent to those skilled in the art. Accordingly,the descriptions of example embodiments do not define or constrain thisdisclosure. Other changes, substitutions, and alterations are alsopossible without departing from the spirit and scope of this disclosure,as defined by the following claims.

What is claimed is:
 1. An apparatus, comprising: a processor; atransmitter coupled to the processor; a receiver coupled to theprocessor; and a memory coupled to the processor, the memory storinginstructions that, when executed by the processor cause the processorto: wake the apparatus from a doze state and cause the transmitter totransmit a PS-Poll frame to an access point; in response to the PS-Pollframe being received at the access point, receive a traffic bufferingbit indicating that traffic for the apparatus is buffered by the accesspoint and that a data frame is available to transmit to the apparatus,the traffic buffering bit being included in an acknowledgement framefrom the access point that is received by the receiver; detect a frametransmitted by a wireless station that is not for the apparatus, thewireless station being different from the access point, after theacknowledgement frame indicating that the data frame is available isreceived by the receiver and before the receiver receives the data frametransmitted by the access point; in response to detecting the frametransmitted by the wireless station that is not for the apparatus, causethe apparatus to re-enter the doze state before receiving at theapparatus the data frame transmitted by the access point; wake the firstwireless station from the doze state a second time; and receive dataincluded in the data frame transmitted by the access point and receivedby the receiver.
 2. The apparatus of claim 1, wherein the instructionsstored by the memory, when executed by the processor, cause theprocessor to receive, before the receiver receives the acknowledgementframe, an indication of support for a transmission opportunity powersave operation in a specific transmission opportunity, the indication ofsupport for the transmission opportunity power save operation in thespecific transmission opportunity being included in a beacon frame fromthe access point that is received by the receiver.
 3. The apparatus ofclaim 2, wherein the instructions stored by the memory, when executed bythe processor, cause the processor to cause the apparatus to re-enterthe doze state during the specific transmission opportunity in which areceiver of the frame transmitted by the wireless station in thespecific transmission opportunity is not the apparatus.
 4. The apparatusof claim 2, wherein the processor does not receive data included in theframe transmitted by the access point in the specific transmissionopportunity when a receiver of the frame transmitted by the wirelessstation is not the apparatus.
 5. The apparatus of claim 1, wherein theprocessor receives an indication from the access point that the accesspoint supports power efficient low power wireless stations in a basicservice set.
 6. The apparatus of claim 1, wherein the instructionsstored by the memory, when executed by the processor, cause theprocessor to indicate to the access point, during association, that theapparatus is a power efficient low power wireless station.
 7. Theapparatus of claim 1, wherein the instructions stored by the memory,when executed by the processor, cause the processor to wake theapparatus from the doze state after a beacon signal to send the PS-Pollframe from the wireless station to the access point.
 8. The apparatus ofclaim 1, wherein the instructions stored by the memory, when executed bythe processor, cause the processor to wake the apparatus from the dozestate the second time within the same beacon cycle.
 9. An apparatus,comprising: a processor; a transmitter coupled to the processor; areceiver coupled to the processor; and a memory coupled to theprocessor, the memory storing instructions that, when executed by theprocessor cause the processor to: after receiving an indication that afirst wireless station is a power efficient low power wireless station,receive data included in a PS-Poll frame from the first wireless stationthat is received by the receiver; in response to the receiver receivingthe PS-Poll frame, cause the transmitter to transmit to the firstwireless station an acknowledgement frame containing a traffic bufferingbit indicating that traffic for the first wireless station is bufferedby the apparatus and that a data frame containing buffered data for thefirst wireless station is available to transmit; after the transmittertransmits to the first wireless station the acknowledgement frameindicating that the data frame containing buffered data for the firstwireless station is available and before the transmitter transmits tothe first wireless station the data frame containing buffered data forthe first wireless station, receive data included in a data frametransmitted by a second wireless station that is received by thereceiver, the second wireless station being different from the firstwireless station; in response to receiving the data included in the dataframe transmitted by the second wireless station that is received by thereceiver, cause the transmitter to transmit to the second wirelessstation an acknowledgement frame; and after the transmitter transmits tothe second wireless station the acknowledgement frame, cause thetransmitter to transmit to the first wireless station a data framecontaining buffered data for the first wireless station.
 10. Theapparatus of claim 9, wherein the first wireless station enters a dozestate upon determining that the frame transmitted by the second wirelessstation is not for the first wireless station.
 11. The apparatus ofclaim 10, wherein the first wireless station enters the doze state aftertransmitting an acknowledgement frame from the first wireless station tothe receiver that acknowledges the received data frame.
 12. Theapparatus of claim 9, wherein, wherein the instructions stored by thememory, when executed by the processor, cause the processor to indicate,during association, that the apparatus supports power efficient lowpower wireless stations in a basic service set.
 13. The apparatus ofclaim 9, wherein the instructions stored by the memory, when executed bythe processor, cause the processor to receive, during association, anindication that the first wireless station is a power efficient lowpower wireless station.
 14. The apparatus of claim 9, wherein theinstructions stored by the memory, when executed by the processor, causethe processor to cause the transmitter to transmit a beacon signalbefore receiving the indication that the first wireless station is thepower efficient low power wireless station.